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Listeria in food


Last updated: 22 December 2020

What is it?

  • Listeria monocytogenes (Listeria) is a type of bacteria commonly found in soil, water, sewage and the gut of animals
  • Listeria can grow in cold conditions, even in refrigerated food
  • Foods at higher risk of contamination include ready-to-eat foods (foods that won’t be further cooked) such as pre-prepared salads and fruit, soft cheese, deli meats, smoked seafood, soft serve ice cream, unpasteurised milk and raw vegetables

What's the risk?

  • Listeria can cause an illness called listeriosis
  • Listeriosis is rare but for pregnant women, the elderly and people with weak immune systems the illness can be very serious
  • Listeria may cause pregnant women to miscarry or the baby can be born prematurely or stillborn
  • Even a small amount of Listeria in food can cause illness

Reduce your risk

  • If you are pregnant, elderly or have a weak immune system, avoid pre-prepared ready-to-eat foods, especially those mentioned above
  • Don’t eat foods that are past their use by date
  • Cook food thoroughly and eat it immediately
  • Refrigerated leftovers should be eaten within 3-4 days (or within 1 day for vulnerable people)
  • Reheat food thoroughly – until it is steaming hot (75°C)
  • Make sure your fridge is running at 5oC or colder
  • Wash raw fruit and vegetables thoroughly under running water
  • Avoid cross contamination − use separate cutting boards and knives for raw and ready-to-eat food, and store cooked food separately from raw foods
  • Wash your hands with soap and dry them before preparing and eating food
  • Keep your kitchen and equipment clean.

Symptoms of listeriosis

  • Symptoms usually start about 3 weeks after eating contaminated food, but can present from 3 to 70 days from infection
  • Mild symptoms (in healthy people) include fever, headache, muscle aches, nausea and diarrhoea
  • More severe illness can cause blood poisoning, inflammation of the brain and spinal cord, miscarriage or death

For further information on listeria in food, see our web page on Listeria and food - advice for people at risk, and watch our animation.


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